Mobile electronic three-dimensional compass

ABSTRACT

The invention relates to a mobile electronic system. In order to expand and enhance the usability of the mobile electronic system, it is proposed that it comprises a 3D magnetometer  51  performing magnetic measurements in three dimensions and providing data indicative of the current posture of the mobile electronic system based on these measurements. Further, it is proposed that the mobile electronic system comprises processing means  52, 54  processing the data provided by the 3D magnetometer  51  for enabling a posture related presentation of information via output means  12, 42  of the mobile electronic system. The invention relates equally to components of such a system and to a corresponding method.

FIELD OF THE INVENTION

The invention relates to a mobile electronic system comprising meanswhich realize the function of a compass and to components of such asystem. The invention relates equally to a method for a mobileelectronic system.

BACKGROUND OF THE INVENTION

It is known from the state of the art to provide mobile electronicsystems with a two dimensional compass. Such a mobile electronic systemsmay be included for instance in a communication device like a mobilephone.

In German patent application DE 198 37 568 A1, it is proposed to providea Personal Digital Assistant (PDA) with a Global Positioning System(GPS) receiver, a mobile communication unit and a compass. The compassis used for determining the current orientation of the PDA, which isrequired for realizing navigation functions in the PDA.

In British patent application GB 2 298 539 A, it is equally proposed toprovide a hand held device containing a GPS receiver with a compass. Adisplayed information relating to the current environment, e.g. a map,is rotated in accordance with the respective orientation of the device.

Further, it is proposed in international application WO 01/88687 A2 toaccess context information with a user equipment, e.g. a mobile phone.The context information is downloaded from a network based on a locationservice. Then, the orientation of the user equipment is determined usinga compass in the user equipment. Once the orientation is known, a visualuser interface is generated at the user equipment for displaying thedownloaded context information. In order to select a virtual objectdisplayed in the visual user interface, the user can point to therespective object by orienting the user equipment. During the movementof the user equipment, the displayed virtual objects move accordingly infront of the user.

A mobile electronic system may also comprise an Inertial NavigationSystems (INS), which INS can be used for determining the position of themobile electronic system. In such a system, it is essential thatprovided heading information remains accurate along time, since evensmall errors in the computed orientation cause significant errors to theposition estimate. Traditionally, IN Systems utilize gyro-compasses toensure an accurate heading. Gyro-compasses, however, have severaldisadvantages. They constitute quite expensive components due to theircomplicated electronics. Moreover, they are physically large sensors andcan thus not be implemented in small modules. The use of a conventional3-axis gyro-compass in a small INS is not feasible at all, since itrequires even more complex electronics and its power consumption is muchhigher. As a result, it is more expensive and it also requires morespace. A 3-axis operation, however, is essential for an accurate INS.

SUMMARY OF THE INVENTION

It is an object of the invention to expand and enhance the usability ofa mobile electronic system.

This object is reached according to the invention with a mobileelectronic system, which comprises output means enabling a presentationof information to a user of the mobile electronic system. The proposedmobile electronic system further comprises a 3D (three-dimensional)magnetometer performing magnetic measurements in three dimensions andproviding data indicative of the current posture of the mobileelectronic system based on these measurements. The 3D magnetometer thusrealizes the functions of a 3-dimensional compass. Finally, the proposedmobile electronic system comprises processing means processing the dataprovided by the 3D magnetometer for enabling a posture relatedpresentation of information via the output means.

The mobile electronic system may be a single unit or be composed ofseveral units. It may be comprised, for example, completely in a userequipment like a mobile communication device. Alternatively, the mobileelectronic system may comprise for example a user equipment includingthe output means, while at least the 3D magnetometer is included in aseparate, complementary unit which can be connected to the userequipment. In the latter case, the connection should be rigid so thatthe posture of the complementary unit with the 3D magnetometercorresponds always to the posture of the user equipment. The processingmeans can then be included in either of the two units or be distributedto the two units. The unit comprising the output means may be forexample a mobile phone and the complementary unit comprising the 3Dmagnetometer a functional cover for the mobile phone.

The object of the invention is equally reached with a correspondingcomplementary unit and with a corresponding user equipment comprisingeither the part of the proposed mobile electronic system not comprisedby a complementary unit or the entire proposed mobile electronic system.

The object of the invention is further reached with a correspondingmethod for a mobile electronic system. The method comprises in a firststep performing magnetic measurements in three dimensions in the mobileelectronic system. The method comprises moreover determining dataindicative of the current posture of the mobile electronic system basedon the performed magnetic measurements. Finally, the proposed methodcomprises processing this data for enabling a posture relatedpresentation of information to a user of the mobile electronic system.

The invention is based on the consideration that a 3D magnetometer isable to sense not only the orientation of a device in which it isincluded or to which it is attached in a horizontal plane, like a 2Dcompass, but also its current inclination. This additional data can beemployed for a variety of new or enhanced functions of a mobileelectronic system. It can be used for example to enhance thepresentation of information and/or to select a mode of presentationdepending on the current posture of the mobile electronic device. A 3Dmagnetometer can further be used as main source for heading informationin an inertial navigation system, since it is smaller and less expensivethan a gyro-compass.

Preferred embodiments of the invention become apparent from thedependent claims.

In a preferred embodiment of the invention, the presented informationcomprises compass information.

In another preferred embodiment of the invention, different modes ofpresentation are selected depending on the posture of the mobileelectronic system. In case the output means comprise a display and themobile electronic system is held basically horizontally, the display andfunctioning can resemble e.g. to a traditional compass. When the mobileelectronic system is held basically vertically, in contrast, thepresentation of information may be switched to some other mode.

In another preferred embodiment of the invention, the output meanscomprise a 3D display for a presentation of compass information, e.g. apresentation of a floating compass. This enables a new user experiencecompared to a 2D electrical compass, which cannot even be used in freeposture.

In another preferred embodiment of the invention, the system comprisesadditional sensor means, which provide further measurement data. Thesefurther measurement data can be employed by the processing means inaddition for enabling the posture related presentation of informationvia the output means. The additional measurement data allow theprocessing means to adjust the functionality of the system to theenvironment and/or to a user profile. For example, data on the postureand the characteristics of the movements of the mobile electronic systemcan be used to change the functionality. The adjustment of thefunctionality may comprise for example an adjustment of the presentationof information via the output means and/or an adjustment of a filteringof signals provided by the 3D magnetometer.

The additional sensor means may comprise for example a 2D or 3D linearaccelerometer measuring the acceleration of the mobile electronic systemin two or three dimensions, respectively, or a 3D angular accelerometermeasuring the angular acceleration of the mobile electronic system inthree dimensions.

Since a magnetic compass is subjected to unpredictable disturbances, a3D angular accelerometer can be used to verify whether sudden changes ofdirection indicated by the 3D magnetometer actually occurred or whetherthere was only a temporary disruption. This enables a compensation ofrandom magnetic disturbances. From an implementation point of view,angular accelerometers have the advantage that they do not require anydedicated electronics and that they can be read with the sameelectronics as linear accelerometers. Angular accelerometers are alsoinexpensive and smaller than gyro-compasses.

In case a 3D angular accelerometer is used as additional sensor means,the 3D magnetometer may provide first data indicating a current headingof the mobile electronic system, while the 3D angular accelerometerprovides second data indicating a current heading of the mobileelectronic system. Moreover, the processing means may comprise acomplementary filter combining the first and second data, in order toobtain a particularly reliable information on the current heading of themobile electronic system.

A combination of a 3D magnetometer and a 3D angular accelerometer is ofparticular advantage for an INS realized in the mobile electronicsystem.

It is understood that data provided by the 3D magnetometer may be usedfor various applications in the mobile electronic system.

BRIEF DESCRIPTION OF THE FIGURES

Other objects and features of the present invention will become apparentfrom the following detailed description considered in conjunction withthe accompanying drawings, wherein:

FIG. 1 schematically illustrates a first posture dependent display modeemployed in a first embodiment of the invention;

FIG. 2 schematically illustrate a second posture dependent display modeemployed as first example in the first embodiment of the invention;

FIG. 3 schematically illustrate a second posture dependent display modeemployed as second example in the first embodiment of the invention;

FIG. 4 a-d schematically illustrate a simulation of a floating compassin a second embodiment of the invention;

FIG. 5 is a block diagram of a complementary filter employed in a thirdembodiment of the invention; and

FIG. 6 is a block diagram of a complementary filter in one compass planethat is based on two axis of a magnetometer and on an angularaccelerometer.

DETAILED DESCRIPTION OF THE INVENTION

In a first embodiment of the invention illustrated in FIGS. 1 to 3, amobile phone 10 can be employed as a two-dimensional compass with twodifferent presentation modes. The mobile phone 10 comprises buttons 11,a display 12, a 3D magnetometer, a 3D accelerometer and processingmeans.

The 3D magnetometer constantly performs magnetic measurements in allthree dimensions. The measurement results, which constitute aninformation on the current posture of the mobile phone 10, are providedto the processing means. Moreover, the 3D accelerometer constantlyperforms acceleration measurements in all three dimensions. Also thesemeasurement results, which allow a to draw conclusions as to the currentvelocity of the mobile phone, are provided to the processing means.

As long as the measurement results by the 3D accelerometer indicate thatthe mobile phone is only moved slowly, a fast acting filtering softwareis activated in the processing means for filtering the measurementresults provided by the 3D magnetometer. The fast acting filteringsoftware filters the measurement results with an integration period ofabout 1 to 3 seconds, which removes e.g. the influence of handvibrations, of by-passing cars and of disturbances in the magneticfields of the earth.

In case the measurement results by the 3D accelerometer indicate, incontrast, that the mobile phone is moved with an increased velocity, aslow filtering software is activated in the processing means forfiltering the measurement results provided by the 3D magnetometer. Theslow filtering software filters the measurement results with anintegration period of about 5 to 10 seconds. The slow filtering isactivated for instance in case the compass function is to be used whilethe user is driving in an urban city environment, in order to filtertemporary fluctuations in the magnetic field due to bypassing trams,buses, buildings, metal constructions, etc.

The filtered measurement results of the 3D magnetometer are thenevaluated by the processing means for presenting compass information onthe display 12 of the mobile phone 10.

When the magnetic measurements indicate that the phone 10 is positionedbasically horizontally, which may e.g. be the case when a user of thephone 10 is walking, a first mode of presentation is selected by theprocessing means. In the first mode of presentation, the display 12 andthe functioning resembles a traditional compass.

For this first mode of presentation, the processing means determine thedirection in the horizontal plane to which the top of the mobile phone10 is oriented based on the provided measurement results. Theorientation information contained in the filtered signal is thenreflected by an arrow 13 in a circle 14 on the display 12 of the mobilephone 10, as shown in FIG. 1. The circle 14 with the arrow 13 representa conventional compass. Accordingly, the arrow 13 is always orientedsuch that it points to the North. Alternatively, any other predetermineddirection could be indicated based on the filtered signals. The fastacting filtering, which is activated when the user is walking, allowsthe user to find North without unnecessary delays.

When the magnetic measurements indicate, in contrast, that the degree ofan inclination of the mobile phone exceeds a predetermined value, whichmay e.g. be the case when a person is tilting the phone or when it iskept in a car stand, a second mode of presentation is selected.

For the second mode of presentation, the processing means determine theorientation of the back of the tilted mobile phone based on the filteredmagnetic measurement results. The presentation of the determined compassinformation differs moreover from the presentation in the first mode ofpresentation, since a simulation of a conventional compass as in thefirst mode of presentation is not appropriate with a tilted phone.

Two possibilities for the second mode of presentation are illustrated inFIGS. 2 and 3.

In the first possibility illustrated in FIG. 2, the presentation on thedisplay 12 resembles a “marine compass”. In a first row, the currentorientation of the phone is indicated by the points of the compass North“N”, East “E”, South “S” and West “W”, while in a second row, thecurrent orientation of the phone is indicated by corresponding degrees“90”, “180”, “270” and “360”. In the situation depicted in FIG. 2, theuser of the phone faces North-West or 315°, since the center of thefirst row lies between an indicated “N” and an indicated “W”, and thecenter of the second row lies between indicated “360” and “270” degrees.

The second possibility for the second mode of presentation illustratedin FIG. 3 is provided in order to enable a user of a mobile phone 10 toeasily keep a preset target direction. The direction may be entered viathe buttons 11 of the mobile phone 10. The desired direction can beselected in particular using the points of the compass or acorresponding indication in degrees.

The direction information contained in the filtered magnetic measurementresults is then reflected by a simple arrow pointing in the desireddirection on the display.

FIG. 3 presents the view of a driver of a car who is using the mobilephone 10 with the second possibility for the second mode ofpresentation. The mobile phone 10 is fixed in a car stand, which isconnected to the dashboard on the right hand side of the steering wheelof the car. In the presented example, the arrow 15 shown on the display12 of the mobile phone 10 indicates that the desired direction isstraight ahead.

With the second possibility for the second mode of presentation, thus asimplified navigation system is provided. It may be used for examplewhen driving in an urban environment towards an airport, which is lyingin a known direction. The slow filtering, which is activated when theuser is driving, ensures that most magnetic disturbances are not visiblein the presentation of the compass information.

In a second embodiment of the invention, a mobile phone can be employedfor simulating a floating three-dimensional compass, e.g. a floatingnavy compass. Like the mobile phone of the first embodiment, the mobilephone of the second embodiment comprises buttons, a display, a 3Dmagnetometer, a 3D accelerometer and processing means. In the secondembodiment, however, the display is a 3D display.

The 3D magnetometer constantly performs magnetic measurements in allthree dimensions, which provide an information on the current posture ofthe mobile phone. The 3D accelerometer further measures theaccelerations of the mobile phone in all three dimensions.

The measurement results of the 3D magnetometer and the 3D accelerometerare used by the processing means for presenting the floating compass onthe display of the mobile phone. More specifically, the measurementresults provided by the 3D accelerometer are used by the processingmeans for filtering the measurement results provided by the 3Dmagnetometer with a delay, similarly as described for the firstembodiment. Then, the processing means show a 3D compass on the 3Ddisplay, of which the orientation corresponds to the posture informationcontained in the filtered measurement results. The compass isrepresented by the processing means on the 3D display such that a usercan view the compass from all sides by tilting the mobile phone. Due tothe filtering of the signals, the displayed compass follows changes ofthe posture only slowly, resulting in the particular effect of a virtualfloating compass.

FIGS. 4 a-4 d schematically illustrate the presentation of the floatingcompass on the display 42 of the mobile phone for various postures ofthe phone.

The compass is represented as a sphere 43 on the 3D display 42 of themobile phone. The top of the sphere 43, and thus of the virtual compass,is indicated by circles 44. In all four cases illustrated in FIGS. 4 a-4d, the user of the mobile phone is facing South-East (SE). An arrow 45indicating the direction which the user faces is thus labeled “SE”. Thearrow 45 is always pointing to the top 44 of the sphere 43. A circle 46is depicted around the middle of the sphere 43, all points of the circlebeing equidistant to the top 44 of the sphere 43.

FIG. 4 a shows the display 42 in a first situation, in which the mobilephone is hold vertically. The top 44 of the compass is depicted next tothe top 47 of the display 42. The arrow 45 indicating South-East israther short in the first situation.

FIG. 4 b shows the display 42 in a second situation in which, proceedingfrom the first situation in FIG. 4 a, the mobile phone is tiltedsideways to the right. The user has exactly the same view on therepresented compass as in FIG. 4 a. That is, the top 44 of the compassis now depicted next to the upper left corner 48 of the display 42. Thearrow 45 indicating South-East has the same length as in FIG. 4 a.

FIG. 4 c shows the display 42 in a third situation, in which, proceedingfrom the first situation in FIG. 4 a, the mobile phone is tiltedforward. As a result, the bottom of the mobile phone is now somewhatcloser to the user than the top of the mobile phone. The representedcompass appears to be rotated towards the user, since the top 44 of thecompass is shifted in direction of the center of the display 42. Thearrow 45 indicating South-East is slightly longer than in FIGS. 4 a and4 b.

FIG. 4 d shows the display 42 in a fourth situation, in which the mobilephone is hold horizontally. The user of the mobile phone has now a topview on the represented compass. Thus, the top 44 of the compass isdepicted in the center of the visible part of the sphere 43. The arrow45 indicating South-East extends throughout the visible part of thesphere 43. The visible part of the sphere 43 is now limited by thecircle 46 depicted around the middle of the sphere 43.

The second embodiment of the invention is ideal for mobile phones havinga large color display.

In a third embodiment of the invention, a mobile phone is employed forrealizing an INS. To this end, the mobile phone comprises a display, a3D magnetometer, a 3-axis angular accelerometer and processing means.

Measurement results provided by the 3D magnetometer and the angularaccelerometer are used by the processing means for presenting thecurrent heading of the user of the mobile phone on the display. The 3Dmagnetometer provides an excellent long term reference for the angularposition of the device. However, magnetometers are sensitive to externaldisturbances. The angular accelerometer on the contrary presents lownoise operation but poor stability. Thus, the combination of themagnetometer and the angular accelerometer provides means to perform ameasurement with good stability and good tolerance to externaldisturbances.

FIG. 5 is a block diagram which illustrates the processing of thesignals provided by the 3D magnetometer and the angular accelerometer.The block diagram comprises a first block 50 representing the 3-axisangular accelerometer and a second block 51 representing the 3Dmagnetometer. The output of the angular accelerometer 50 is connected tofirst filter means 52 and the output of the 3D magnetometer 51 isconnected to second filter means 53. The outputs of the filter means 52,53 are connected to a summing point 54. The filter means 52, 53 and thesumming point 54, which form a complementary filter, are part of theprocessing means of the mobile phone.

The angular accelerometer 50 measures angular accelerations of themobile phone in any direction proceeding from a point of time at whichthe heading was known until a new point of time t. Based on the measuredmovements and on the last known heading, the angular accelerometer thenestimates the new heading at point of time t and provides acorresponding first heading signal. This first heading signal comprisesthe true heading s(t) at point of time t and a noise component n₁(t),which takes account of errors in the angular measurements.

At the same point of time t, the 3D magnetometer 51 performs in additionmagnetic measurements, in order to determine the current posture of themobile phone. Based on the magnetic measurements, the 3D magnetometer 51then estimates as well the new heading of the mobile phone at point oftime t and provides a corresponding second heading signal. This secondheading signal comprises equally the true heading s(t) at point of timet and a noise component n₂(t), which takes account of errors in themagnetic measurements.

As a result, two redundant measurements of the same signal areavailable. These two measurements can now be combined in a way that themeasurement error is minimized. This is achieved with the complementaryfilter, to which the two heading signals are provided.

The first heading signal is subjected by the first filter means 52 to afiltering function which has a transfer function G(s). Moreover, theresult of the function G(s) is subtracted from 1. The second headingsignal is only subjected by the second filter means 53 to a filteringwith a transfer function G(s). The output of the filter means 52, 53 isthen summed at the summing point 54, resulting in the sum x(t). Such acomplementary filtering allows to filter the noise without distortingthe signal.

The signal output by the summing point 54 thus reflects very closely thetrue heading of the mobile phone at point of time t, and a correspondinginformation can be presented on the display of the mobile phone.

FIG. 6 presents a more concrete implementation of a complementaryfiltering based on the use of an angular accelerometer for compensatingmagnetic field disturbances in the signals of a magnetometer. FIG. 6 ismore specifically a block diagram of a complementary filter for onecompass plane that is based on a two axis magnetometer and an angularaccelerometer. A similar implementation is required for all threedirections.

The block diagram of FIG. 6 comprises two blocks 61, 62 representingmeasurement values m_(x), m_(y) of a 3D magnetometer in a firstdirection x and a second direction y, respectively. The two blocks 61,62 are connected to a block 63 representing compass functions. Theoutput of this block 63 is connected on the one hand via a blockrepresenting a derivator 64 to a first summing point 65 and on the otherhand to a second summing point 66. The block diagram moreover comprisesa block 67 representing measurement values

_(xy) of an angular accelerometer. This block 67 is connected to anintegrator 68 and further to the first summing point 65. The output ofthe first summing point 65 is connected to a block representing anadaptive filter 69. The output of block 69 is connected as well to thesecond summing point 66. A dashed line separates the sensor relatedblocks 61, 62 and 67 on the left hand side from the other, digitalsignal processing related blocks on the right hand side.

The compass signal θ_(xy) that is calculated in block 63 from themagnetometer values m_(x), m_(y) is differentiated in the derivator 64with respect to time in order to remove the constant field value. Theresulting value indicates the angular velocity based on the magneticfield, but includes high frequency disturbances. The correspondingangular acceleration signal

_(xy) is integrated in the integrator 68. The resulting value indicatesthe true angular velocity based on the acceleration of the mobile phone,but comprises a low frequency drift. The time constants of derivator 64and integrator 68 are matched.

The two signals {dot over (θ)}_(xy) output by the derivator 64 and theintegrator 68 are compared by means of the summing point 65 in order toseparate the disturbances and the low frequency drift of the trueangular velocity. The summing point 65 subtracts more specifically thevalue obtained from the derivator 64 from the value obtained from theintegrator 68. The signal is then passed through the adaptive filter 65.The adaptive filter applies a high-pass filtering on the received signalin order to separate the disturbances of the signal. The disturbancesare further integrated in the adaptive filter 65 in order to obtain anestimate of the angular error of the device for the inertial navigationpurposes.

The high-pass filtered estimate of the angular error is then subtractedby the second summing point 66 from the compass heading informationθ_(xy) including disturbances, which is output by block 63. The outputof the second summing point 66 is thus a corrected compass headingθ_(xy,corr) for one compass plane.

The system of FIG. 6 can be further improved by using adaptive filters,such as Kalman filters, for the error signal processing.

It is to be noted that the described embodiments constitute onlyselected ones of a variety of possible embodiments of the invention.

1. A mobile electronic system comprising output means (12,42) enabling apresentation of information to a user of said mobile electronic system;a 3D magnetometer (51) performing magnetic measurements in threedimensions and providing data indicative of the current posture of saidmobile electronic system based on said measurements; and processingmeans (52,54) processing said data provided by said 3D magnetometer (51)for enabling a posture related presentation of information via saidoutput means (12,42), including selecting one of at least two differentmodes of presentation based on said data provided by said 3Dmagnetometer.
 2. The mobile electronic system according to claim 1,wherein said processing means present compass information(13,14,15,43-46) via said output means (12,42) based on said dataprovided by said 3D magnetometer.
 3. The mobile electronic systemaccording to claim 2, wherein said output means comprise a 3D display(42) on which said compass information (43-46) is presented.
 4. Themobile electronic system according to claim 3, wherein said processingmeans present a floating compass (43-46) on said 3D display (42) basedon said data provided by said 3D magnetometer.
 5. The mobile electronicsystem according to claim 1, further comprising additional sensor means(50) providing additional measurement data, wherein said processingmeans use said additional measurement data in addition for enabling aposture related presentation of information (43-46) via said outputmeans (42).
 6. The mobile electronic system according to claim 5,wherein said processing means use said additional measurement dataprovided by said additional sensor means at least for one of thefollowing: adjusting a presentation of information via said output meansand filtering signals provided by said 3D magnetometer.
 7. The mobileelectronic system according to claim 5, wherein said sensor meanscomprise a 2D or 3D linear accelerometer measuring the acceleration ofsaid mobile electronic system in three dimensions.
 8. The mobileelectronic system according to claim 5, wherein said sensor meanscomprise a 3D angular accelerometer (50) measuring the angularacceleration of said mobile electronic system in three dimensions. 9.The mobile electronic system according to claim 8, wherein said 3Dmagnetometer (51) provides first data indicating a current heading ofsaid mobile electronic system, wherein said 3D angular accelerometer(50) provides second data indicating a current heading of said mobileelectronic system, and wherein said processing means comprise acomplementary filter (52-54) combining said first and said second dataindicating a current heading of said mobile electronic system.
 10. Themobile electronic system according to claim 1, realizing an inertialnavigation system.
 11. The mobile electronic system according to claim1, wherein at least said output means are comprised in a user equipment,wherein at least said 3D magnetometer is comprised in a complementaryunit external to said user equipment, wherein said user equipment andsaid complementary unit comprise respective connection means rigidly andelectrically connecting said complementary unit and said user equipmentfor providing signals which are based on magnetic measurements of said3D magnetometer to said user equipment.
 12. A complementary unit for amobile electronic system according to claim
 11. 13. A user equipment fora mobile electronic system according to claim
 11. 14. A user equipmentcomprising a mobile electronic system according to claim
 1. 15. A methodfor use in a mobile electronic system, said method comprising:performing magnetic measurements in three dimensions in said mobileelectronic system; determining data indicative of the current posture ofsaid mobile electronic system based on said performed magneticmeasurements; and processing said data for enabling a posture relatedpresentation of information to a user of said mobile electronic system,said processing comprising selecting one of at least two different modesof presentation based on said data indicative of the current posture ofsaid mobile electronic system.
 16. The method according to claim 15,comprising presenting compass information (13,14,15,43-46) obtained insaid processing.
 17. The method according to claim 16, comprisingpresenting said compass information (43-46) on a display (42).
 18. Themethod according to claim 17, comprising presenting a floating compass(43-46) on a 3D display (42).
 19. The method according to claim 15,further comprising performing additional measurements in said mobileelectronic system, wherein said processing is based in addition onmeasurement data resulting in said additional measurements.
 20. Themethod according to claim 19, wherein said processing comprises usingsaid additional measurement data at least for one of the following:adjusting a presentation of information and filtering signals resultingin said performed magnetic measurements.
 21. The method according toclaim 19, wherein performing said additional measurements comprisesmeasuring the acceleration of said mobile electronic system in threedimensions.
 22. The method according to claim 19, wherein performingsaid additional measurements comprises measuring the angularacceleration of said mobile electronic system in three dimensions. 23.The method according to claim 22, wherein said processing comprisescombining first data indicating a current heading of said mobileelectronic system and second data indicating a current heading of saidmobile electronic system by a complementary filtering, which first datais based on said magnetic measurements and which second data is based onsaid angular acceleration measurement.